auth: Remove "shared" aka "global" secrets.

server/auth/auth_test.go

Index: server/auth/auth_test.go
diff --git a/server/auth/auth_test.go b/server/auth/auth_test.go
index 09d6b49269a81b7b0c3182925ff6ac0bf4b1be97..493edc75e137b89865ddf083ea6876ee771bb2f4 100644
--- a/server/auth/auth_test.go
+++ b/server/auth/auth_test.go
@@ -14,7 +14,6 @@ import (
 	"golang.org/x/net/context"
 
 	"github.com/luci/luci-go/server/router"
-	"github.com/luci/luci-go/server/secrets"
 
 	"github.com/luci/luci-go/server/auth/authdb"
 	"github.com/luci/luci-go/server/auth/identity"
@@ -250,10 +249,6 @@ func (db *fakeDB) IsMember(c context.Context, id identity.Identity, groups ...st
 	return len(groups) != 0, nil
 }
 
-func (db *fakeDB) SharedSecrets(c context.Context) (secrets.Store, error) {
-	return nil, errors.New("fakeDB: SharedSecrets is not implemented")
-}
-
 func (db *fakeDB) GetCertificates(c context.Context, id identity.Identity) (*signing.PublicCertificates, error) {
 	return nil, errors.New("fakeDB: GetCertificates is not implemented")
 }